JOURNAL OF APPLIED ICHTHYOLOGICAL RESEARCH
Year:2013 | Volume:1 | Issue:2|Papers Count:9

A 28-day feeding trial was conducted on the A. guldenstaedtii larvae during the early stages of active feeding, using three live foods, namely Daphnia magna, Artemia urmiana and a mixture of both (Daphnia 50% w/w and Artemia50% w/w) with a feeding frequency of 6 times per day. The healthy larvae of A. guldenstaedtii were provided from the sturgeon center of Marjanii. Having three replicates (100 fish per tank), the fish larvae in three treatments (A, D and D+A) were scheduled and fed based on 30 percent of the body weight in a day by Artemia urmiana nauplii, Daphnia sp. And a mixture of both, respectively. The initial mean body weight of fish larvae was 35.332.50 mg and its density was 2 individuals per liter. This experiment was conducted in a completely randomized design. The fish were weighed individually at the beginning and end of the experiment. The proximate composition of the fish samples (the beginning and end of the experiment), Artemia nauplii, Daphnia and a mixture of them were determined. Maximum protein retention efficiency (72.29%), lipid retention efficiency (14.61%) and energy retention efficiency (44.81%) were obtained in treatments D+A (fish larvae fed with a mixture of Artemia nauplii and Daphnia), while the minimum of protein efficiency ratio (6.18) and energy efficiency ratio were showed in treatments of D and A, respectively. The results of the present observations demonstrated that the exploitation ability of A. guldenstaedtii larvae in using live food was different.

In order to evaluate the diet composition of bartail flathead, sampling was conducted from December 2009 to November 2011. In this study, a total number of 470 fish were measured, out of which 446 pieces were examined. The length-weight ratios were calculated as W=0.000005FL3.07 (n=198, R2= 0.82) for females, W=0.000009FL2.95 (n=248, R2=0.82) for males and W=0.000004FL3.10 (n=470, R2 =0.86) for total fishes. The analysis of FP and IRI results showed that fish (75%) is the main food source for bartail flathead, followed by shrimp (25%) as a secondary food source and crabs and cuttlefish (5%) as accidental food sources. Overall, the analysis of the stomach contents for bartail flathead indicated that this species is a moderate feeder.

‏‏The sand goby Neogobius pallasi (Berg, 1916) belongs to the family Gobiidae which has a wide distribution in the south of the Caspian Sea basin and its tributaries. The purpose of this study was to determine some of the morphological parameters of sand goby and the appropriate characteristics for the separation of populations in Kaboodval, Zaringol and Shirabad Streams. Both males and females consisted of five age groups (0+-4+). Seven meristic and 31 distance-based morphometric characters from 104, 30 and 62 specimens were investigated in three streams during the summer in 2008. The comparison of the morphological characteristics among the samples of sand goby showed the significant differences in three Streams (p<0.05), but principal components analysis (PCA) showed that the low characteristics play a role in the population separation. Only the mouth width, lower jaw and upper jaw coefficients were greater than 0.75. It seems that there is more overlap between the samples of Kaboodwal and Zaringol compared to those of Shirabad. This finding is also consistent with their geographic distances.

This study surveyed Intrabasin variation in the growth models of C. capoeta in 5 streams of Gorganroud River basin during the reproduction season between April and May, 2010 and 2011. A total number of 1500 specimens were caught through electro-shocking. Total length, total weight, sex and b-value were determined. Total length ranged between 4.1 and 20 cm and total weight ranged between 0.81 and 108.34 g in Pishkamer and Tilabad streams, respectively. The growth models were estimated separately for each sex. The b-value ranged from 2.90 for the males of Pishkamer and Tilabad to 3.13 for the females of Chelchai. Growth model was positive allometric (b>3) for most of the females, while the males had different growth models. A comparison between the b-value of the streams can aid the identification of the factors contributing to the growth model of the populations. In fact, different types of habitats differ in their general environmental conditions which can cause reactions. This reflects a change in the body form with population. This variation in the allometry coefficient of C. capoeta suggests different growth strategies for the populations.

The manipulation of river ecosystems through dam construction or other changes transforms their natural state into a reservoir and causes aquatic animals to face new ecological and evolutionary challenges. This study was conducted to survey the impacts of Tarik dam on the body shape of two isolated populations of riffle minnows using the geometric morphometric method. Thirty specimens were captured from each side of Tarik dam. The left side of each specimen was photographed using a digital camera, and eighteen landmark points were digitized on two-dimensional images using TpsDig2. After GPA, landmark data were analyzed using DFA and TtestHotelling and the patterns of body shape differences between two populations were illustrated on a wireframegraph. The Results revealed significant differences between the body shape of the two studied populations (P<0.0001).Body shape differences between the two populations were related to head, snout, anal fin and caudal peduncle regions. These findings suggest that the characteristics of a new reservoir along with geographical separation act as evolutionary factors bringing about change to the morphological attributes of the fish inhabiting these areas.

The phenotype of an organism not only reflects its genome, but also it can display its habitat and life style features. Hence, this study was aimed to apply the landmark-based geometric morphometric method in the study of the phenotypic plasticity of killifish (A. sophiae) from Cheshme-Ali Damghan and Shour river of Eshtehard. A total of 86 specimens were sampled from Cheshme-Ali (52 specimens) and Shour river (34 specimens). The left side of each specimen was photographed using a digital camera and fifteen landmark points were digitized on 2D images using TpsDig2. The landmark data of the two sexes of both populations were analyzed separately using DFA and T-test Hotelling after GPA superimposition. The patterns of body shape differences between the two sexes of both populations were illustrated. The results revealed significant differences between the body shape of two sexes in both populations (P<0.001). The morphological difference patterns between the two sexes were found in the depth of the body and caudal peduncle and the position of the pectoral fin. The findings of this study suggest that different characteristics of the habitats have driven changes in the morphological attributes of the inhabitant killifish populations along with geographical separation as evolutionary factors.

This study was carried out from May 2011 to June 2012 in order to identify the fish species and their abundance in Hoor-Al azim wetland. Sampling was done using Gill nets on a monthly basis. According to the results 15 species from 3 families were identified. Carasobarbus luteus at 28.7% and Mesopotamichthys sharpeyi at 24.6% had the highest frequency. The highest number of species were observed in autumn with 11 species at Rofaye station and the lowest number of species were in summer with 7 species at shat Ali station.

O. argyrogramma is the only species of the genus Oxynoemacheilus. It is distributed in the freshwaters of Iran and Iraq. The present paper reports a study carried out to investigate the genetic diversity and population structure of O. argyrogramma in Sepidbarg and Gamasiab river basins in Iran. 100 samples (50 samples from each river) were used in this survey. Microsatellite markers were increasingly used in population genetics studies. In this study, a total number of three microsatellite loci and two populations were studied. The average number of allele levels in the population was 13, which was more than the reported values for freshwater fishes. The expected and observed heterozygosity means were 0.652 and 0.876, respectively. Approximately all of the loci showed a deviation from the Hardy-Weinberg equilibrium. The genetic similarity and distance between the two populations were 0.346 and 0.707, respectively. According to the analysis, it seems that O. argyrogramma has a desirable genetic diversity in the investigated regions.